The impact of cognitive load on volitional running, kayaking, rock climbing and arithmetic tasks and the effect of fatigue on risk perception.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The effects of physical activity on cognition and the effects of cognitive load on physical activity are complex. Both the nature of the physical activity and the cognitive task may influence the interactive effects of performing a physical task concurrently with a cognitive task. In a previous study examining the impact of increased cognitive load on outdoor running speed and the impact of outdoor running on cognitive performance, Blakely et al (2015) found running speed decreased as cognitive load increased. They also found that the impact of running itself on cognitive performance occurred when the cognitive task was itself demanding (high cognitive load). In the current study we modified the experimental task in order to rule out peripheral sensory, not central or executive, interference and we also incorporated heart rate measures and VO2 max estimates. Twelve runners completed five conditions, two seated cognitive tasks (one low load and one high load), two dual running cognitive tasks and one run only. Results were similar to the original experiment, as the cognitive task became more difficult, voluntary running speed decreased. Also the effects of running on cognitive performance (counting) were found only when the cognitive task was high load.
Twelve people participated in a dual-kayak cognitive counting task experiment, during which they completed five conditions, two dual tasks, two seated tasks in either low or high load and one kayak only task (control). They used their own paddling gear and were played a counting task designed to tax working memory through headphones, giving a verbal response to report the fourth tone counted of either the low tone only (low load) or all three tones simultaneously (high load). Results were similar to the running experiment, the low load counting task showed no difference to the control condition but the high load task did. Participants did however perform better in the control conditions overall than in the dual tasks. Kayak speed results were mostly as expected; as the task became more difficult, kayak speed decreased. There was a drop between control (paddle only) and the low load conditions that didn’t drop much further in the high load condition. This suggests that kayak performance was affected by the addition of a complex thinking task even at low load showing kayak performance is particularly susceptible to cognitive resource interference.
Rock climbing is a particularly cognitively demanding sport. Planning, movement, reaching, posture control, and fear of falling have all been evidenced to use cognitive attention (Bourdin, Teasdale, & Nougier, 1998; Green et al., 2014; Green & Helton, 2011; Teasdale, Bard, Larue, & Fleury, 1993). For these reasons it was chosen to compare with previous dual running and kayaking experiments that used a counting task as the dual task (Blakely et al., 2015). Using an identical dual task experiment design as previous experiments (chapters two and three), rock climbers completed five conditions, two dual, two single and one climb only. The results showed a difference between the single and dual tasks in the low and high load conditions for counting accuracy. Rock climbing task performance was no different in the single task compared to the combined dual tasks, but there was a difference between the high and low load conditions. This interesting result suggests that the physical task was mentally prioritised over the cognitive task (contrary to the other experiments).
A simple maths equation task was developed as a comparative measure to the physical activity tasks and was designed to investigate interference to the tone counting task and as a seated control to the physical tasks. Participants completed the tone counting task at the same time as a basic arithmetic task on a computer for the dual task conditions. They were required to complete addition or subtraction up to ten, and only correct responses were counted. Performance accuracy on the counting task was worse when comparing the single and combined dual tasks, and worse in the high load than the low load. Participants completed less maths addition and subtraction equations (comparison to the physical tasks) in the single than the dual condition and in the high load compared with the low load conditions. This was the same as the running and kayak experiments (chapters 2 & 3) and to be expected. The addition and subtraction tasks as well as the counting task is an example of the most overlap two tasks share in resource availability according to multiple resource theory.
The interaction between cognitive tasks and physical activity is producing interesting insight about our mental and physical performance limitations. Some research has also shown that as time goes on, cognitive and physical performance decreases, potentially due to a decline in pre frontal cortex (PFC) blood flow and oxygenation (Liu et al., 2010;Mehta & Parasuraman, 2013). This phenomena, commonly known as cognitive fatigue has implications for physical performance because the decline in cognitive resources means less attention resource is available for things like volitional control. When the PFC is fatigued it may also alter decision making, specifically risk perception (Breakwell, 2014). Due to reduced resources it is possible that we adopt conservative approaches to risk so we don’t come to harm. Therefore cognitive fatigue may directly impact risk perception. To test this theory, participants were divided into one of two groups, cognitive fatigue or control, and completed 20 minutes of either a dual vigilance task or nothing at all. Upon completion they rated pictures of cycle-ways for their riskiness. The cognitive fatigue group rated the pictures as more risky than the control group which indicates a relationship between fatigue and risk. MRT states that as resources are depleted, processing efficiency of other processes decreases, in this case as resources deplete feelings of fatigue and perception of risk increases.
Subjective measures were taken from full and half marathon runners, before and after the Queenstown marathon. Participants volunteered to fill out a questionnaire rating their risk perception of cycle-ways before running, and then after running. They viewed 11 pictures of cycle-ways and answered three questions about those pictures. The three questions were; 1.How likely do you think it is that you could come to harm cycling through this environment? 2. How severe are the dangers you could potentially face cycling through this environment? 3. How well do you think you could control any potential dangers while cycling in this environment? The after running group also received a NASA-TLX and a subjective flow state questionnaire. Averages of each question were calculated of the 11 pictures. The full and half marathon runners results were combined and the after running group rated the pictures as more risky than the before running group. The pictures were not rated as more risky in the after compared to before groups when the full and half marathon groups were analysed separately. Removing question three (because it asks about control of risk) meant the full marathon group rated the pictures as riskier than the half marathon group. NASA-TLX results for mental and physical fatigue showed the marathon group rated their run as more physically and mentally tiring than the half marathon group. Interestingly both groups rated their mental fatigue as significantly higher than their physical fatigue. The short flow state scale was rated highly by all participants (M=4.4) on a scale from 1-5, suggesting a ‘flow state’ was experienced by most. The full marathon group rated themselves significantly higher on the scale than the half marathon runners. The authors suspect that this might be due to the mental fatigue of full marathon runners leading them have depleted cognitive resources and in turn adopt a resource conservative mental state that presents as a flow state feeling. The questionnaires show with more fatigue, risk perception increases, that subjective mental fatigue is greater than physical fatigue in the full and half marathons and that fatigue and reports of flow state increase in the full marathon group when compared to the half marathon group. These results reflect the role of cognition in endurance physical tasks and fatigue. Continuing with future experiments along this theme, a physical risk of falling (leap of faith) could be completed after a cognitively fatiguing task to directly measure physical risk perception.